MARTIN: Time for sports, and we're talking baseball this morning because it is an important time of year for aspiring major leaguers - time when the biggest stars from the minor leagues get called up to the big leagues. But, like most things in baseball, it's full of complicated twists and crazy rules, which means we need to call in Mike Pesca to explain. Hi, Mike.

MIKE PESCA, BYLINE: Hi. Thanks for the call-up.

MARTIN: You bet. So, this is tricky. Seems like if I run a major league team and I have some great guys in my minor league farm teams, I can just promote them as soon as I need them, right?

PESCA: It would seem, and that is in fact the case. But, like everything with baseball - as you say - it gets a little tricky because of two things. One, is because baseball is unique but the other thing is that baseball is the same as every other business. Now, the same part is this: every business wants to pay its employees as little as possible while, you know, everyone is happy about things. So, you know, Major League Baseball, they know that if a team knows that if keeps its players for three years, they get that player's services at the league minimum. That's a good deal for teams, and teams that have to operate on very tight budgets, like a lot of young players that teams control and they pay them the league minimum. Now, here's the unique thing. Unlike every other sport, you know, football - you draft a player, he starts the season, you're done. You calculate when he played by the whole season. Basketball, same thing. But with baseball, since players start all different times, there's all different ways to calculate who gets the raise after a certain amount of time. So, the calculation isn't just a straight three years. It's three years but there's a whole bunch of other guys. A small, like, you know, quarter of the guys get paid before everyone else. If you call these group of players up early, if you call them up, you know, in the beginning of the season, you're going to wind up paying them earlier. Now, it would be nice - and let me just say this.

MARTIN: OK.

PESCA: If on July...

MARTIN: You can hear me being confused.

PESCA: Yeah, I know. It would be nice if the rule were, hey, everyone who's playing before July 1st gets counted with one group of players, and everyone who's playing after July 1st gets counted with another group of players. But they don't have an arbitrary date. They do it by the percentage of the total players in terms of league time. So, all the teams are looking at each other kind of waiting for everyone to call up their other players so that when a team calls up its player it gets them on the cheek. It doesn't always work out. It's a huge waiting game. It's kind of a hassle.

MARTIN: My brain is about to explode. But I think I get it. So, does that mean that when these coaches are looking at each other, there's a standoff between teams. Do they sometimes just not call anyone up?

PESCA: That is exactly what happens. So, in a real life example, the L.A. Dodgers, a rich team, they don't really care about the consequences that much of when they have to pay players. They called up this great young people, Yasiel Puig, makes a huge impact. He's setting the world on fire in L.A., like four home runs in his first five days. This is how it should be. If this other team, the Tampa Bay Rays, you know, the poorest team in the league, just about - one of the poorest - they have this great player named Wil Myers. Wil Myers just hit a game-winning home run yesterday for the AAA Durham Bulls. There's only one reason why Wil Myers is not in the major leagues; it's 'cause the Tampa Bay Rays don't want to have to pay him. They figure if they drag their feet for a while, they could get by without Wil Myers. But the Rays really need Wil Myers. They went through this a couple of years ago with Desmond Jennings. And all their fans are saying, come on; bite the bullet. Call up Wil Myers.

MARTIN: It doesn't pay to be that good in the minor leagues.

PESCA: Well, it's more like there's pennywise and pound foolish, if I'm getting that thing right. I think the Rays need to call this guy up.

MARTIN: What's your curveball this week?

PESCA: Well, let's stick with baseball, but baseball thousands of miles away, the Japanese baseball league. Homers were up this year - like I have to tell you, Rachel. I know you're a huge fan of the Nippon-Ham Fighters, right. But it was up to a tremendous degree. They were going to hit 50 percent more home runs. What's the explanation. The league assured everyone, look, all we know is that the balls are no livelier than they ever been. That's the only thing we can assure you. Maybe it's that they're playing in domes. Maybe it's foreign hitters. And so it comes out last week that in fact the balls were livelier than they usually are.

MARTIN: They're cheating.

PESCA: Yeah, yeah. Well, they're not cheating, but they just put in these bouncier balls. And as a result, home runs, extra-base hits have been up. The commissioner of the league have apologized. Some are calling for his head. But in reality, what can you do? You just have bouncier baseballs.